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Code No: 56026 :2: Set No. 1 II Fill in the blanks 11. Non-coherent detection of FSK signal results in ____________________ 12. _____________ is used as a Predictor in a DPCM transmitter. 13. The Nyquist's rate of sampling of an analog signal S(t) for alias free reconstruction is 5000samples/sec. For a signal x(t) = [S(t)]2 ,the corresponding sampling rate in samples/sec is __________________ 14. A Matched filter is used to __________________________ 15. A signal extending over -4v to +4v is quantized into 8 levels. The maximum possible quantization error obtainable is _____________V. 16. The advantage of DPCM over Delta Modulation is _________________________ 17. The phases in a QPSK system can be expressed as ______________________ 18. The Synchronization is defined as _______________________ 19. The sampling rate in Delta Modulation is _______________than PCM. 20. The bit error Probability of BPSK system is __________________that of QPSK.
code No: 56026 Set No. 2 JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD III B.Tech. II Sem., I Mid-Term Examinations, February – 2012 DIGITAL COMMUNICATIONS Objective Exam Name: ______________________________ Hall Ticket No. Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 10. I Choose the correct alternative: 1. The Auto-correlation function of White Noise is [ ] A) Impulse function B) Constant C) Sampling function D) Step function 2. The minimum band width required for a BPSK signal is equal to [ ] A) one fourth of bit rate B) twice the bit rate C) half of the bit rate D) bit rate 3. Companding results in [ ] A)More S/N ratio at higher amplitudes of the base band signal B) More S/N ratio at lower amplitudes of the base band signal C) Uniform S/N ratio throughout the base band signal D) Better S/N ratio at lower frequencies 4. A uniform quantizer is having a step size of .05 volts. This quantizer suffers from a maximum quantization error of [ ] A) 0.1V B) 0.025 V C) 0.8 V D) 0.05 V 5. In Non-Coherent demodulation, the receiver [ ] A) relies on carrier phase B) relies on the carrier amplitude C) makes an error with less probability D) uses a carrier recovery circuit 6. The advantage of Manchester encoding is [ ] A) less band width requirement B) less bit energy required for transmission C) less probability of error D) less bit duration 7. Granular Noise in Delta Modulation system can be reduced by A) using a square law device B) increasing the step size C) decreasing the step size D) adjusting the rate of rise of the base band signal 8. The minimum band width required to multiplex 12 different message signals each of band width 10KHz is [ ] A) 60KHz B) 120KHz C) 180KHz D) 160KHz 9. In 8-PSK system, adjacent phasors differ by an angle given by ( in degrees) [ ] A) n/4 B) n/8 C) n/6 D) n/2 10. Band Width efficiency of a Digital Modulation Method is [ ] A) (Minimum Band width)/ (Transmission Bit Rate) B) (Power required)/( Minimum Band width) C) (Transmission Bit rate)/ (Minimum Band width) D) (Power Saved during transmission)/(Minimum Band width) Cont……2
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DC COURSE FILE
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GEETHANJALI COLLEGE OF ENGINEERING
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Convolution Codes: Encoding, decodi
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III. To inculcate positive attitude
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7. Importance of the course and how
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DC 12: Compute the power and bandwi
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10. Course mapping with PEO’s and
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13.Micro plan : Sl. no Unit No. Tot
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14.Detailed Notes UNIT 1 : Elements
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A communication system may transmit
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the wavelength is extremely long, m
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asic elements of digital communicat
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4. Channel introduced many types of
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5. Bandwidth is another scarce reso
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Pulse Code Modulation ‣ PCM gener
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77777333333333333333333333333333333
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• The most common technique for s
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Pulse Code Modulation (PCM) : • P
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Figure 3.11 Illustration of the qua
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Quantization (nonuniform quantizer)
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Time-Division Multiplexing(TDM):
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Let m n where T The error signal is
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3. Simplify receiver design Because
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Figure 3.27 Block diagram illustrat
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Adaptive Differential Pulse-Code Mo
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ASK, OOK, MASK: • The amplitude (
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Frequency Shift Keying: • One fre
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s t Acos 2f ct 3 Acos 2f
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QAM and QPR: • QAM is a combinati
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Generation and Detection of Coheren
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Figure 6.29 Signal-space diagram fo
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UNIT 3 Base Band Transmission And O
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• The tails of hI(t) decay as 1/|
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• precoding d b d k k k2 symbol 1
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h( t) N 1 n w n sin c t T b
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• Equalization : to compensate fo
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e n y n 2E en 2E en 2Eenxnk
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- Flexibility - Same H/W may be tim
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Interpretation of Eye Diagram:
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The set of source symbols is called
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We will usually neglect to mention
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Note that if Condition1 is satisfie
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where dmin is the minimum Hamming d
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Linear Block Codes - example 1: •
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• S null can be represented by it
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G 1 0 I | P 0 0 0 1 0 0 0 0
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• Compared with the systematic co
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Convolutional Codes ◊ The encoder
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Convolution Codes ‣ Encoding, ‣
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x m m ''' j j 2 j Here each messa
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Representing convolutional codes: C
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- encoder state diagram for (n,k,L)
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• For this reason the non-survive
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sequence is 1 1 0 0 0 0 0 (why?). N
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Page 121 and 122: correct:1+1+2+2+2=8;8 ( 0.11) 0.88
Page 123 and 124: Motivation: Performance of Turbo Co
Page 125 and 126: Performance as a Function of Number
Page 127 and 128: General Model of Spread Spectrum Sy
Page 129 and 130: Slow and Fast FHSS: • Frequency s
Page 131 and 132: - 10 bit spreading code spreads sig
Page 133 and 134: Direct Sequence Spread Spectrum Usi
Page 135 and 136: 15.Additional Topics: Voice coders
Page 137 and 138: 'Toll Quality' voice coders, such a
Page 139 and 140: The well-known Shannon-Hartley law
Page 141 and 142: its for a known permutation of the
Page 143 and 144: 16. Question papers: B. Tech III Ye
Page 145 and 146: e received code word 110110. Commen
Page 147 and 148: 17. Question Bank 1. (a) State and
Page 149 and 150: 21. A Discrete Memory less Source (
Page 151 and 152: 19. Unit wise Bits CHOOSE THE CORRE
Page 153 and 154: (d) 5 Answers 1.C 2.D 3.B 4.A 5.C 6
Page 155 and 156: (b) its capacity gets doubled (c) i
Page 157 and 158: (d) 6 5. The cascade of two binary
Page 159 and 160: CHOOSE THE CORRECT ANSWER 1. The mi
Page 161 and 162: 2.C 3.C 4.A 5.D 6.C 7.B 8.B 9.B 10.
Page 163 and 164: (b) H(X/Y)=1bit/message (c) H(X,Y)=
Page 165 and 166: (d) log m bits/symbol 6. Theencoder
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Page 173 and 174: B) (Power required)/( Minimum Band
Page 175 and 176: A) 5 B) 4 C) 2 D) 3 3. Which of the
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Page 179 and 180: A) maximum when the source is conti
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Page 183 and 184: Code No: 07A5EC09 Set No. 2 JAWAHAR
Page 185 and 186: Cont…..2 Code No: 07A5EC09 :2: Se
Page 187 and 188: 8) For the data word 1110 in a (7,
Page 191 and 192: a) 0 bits b) 1 bit c) 2 bits d) inf
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Page 199 and 200: Amplitude of 1v.This speech signal
Page 201 and 202: . Self Information c. Logarithmic m
Page 203 and 204: 75. What are the advantages and dis
Page 205 and 206: 22. Discussion Topics: Data transmi
Page 207 and 208: Applications and history Data (main
Page 209 and 210: o o Mesh network Wireless network A
Page 211 and 212: 25. STUDENTS LIST B.TECH III YEAR I
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Page 215 and 216: Group 8: 36 13R11A04K1 POLISETTY VE
Page 217 and 218: Unit 2 Pulse-Amplitude Modulation :
Page 219 and 220: Unit 3 Differential Pulse-Code Modu
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MISSING TOPICS UNIT 1 Hartley's law
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encoding the desired information an
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• f c denotes center frequency
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An interleaver installed between th
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Subject Contents 1.7. 1. Synopsis p
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